DIY Mini-Tubbing Guide - Rubber Room

1/15While this story does not cover suspension mods, we'll mention that the mini-tub process can be easiest with the entire rearend and suspension removed from the car.

Mini-tubbing is the act of widening a car's rear wheelwells, moving the inner halves inboard to the location of the stock frame-rails to achieve maximum tire clearance without major frame hacking. It's a mod that dates back to the early '60s and has mostly been used for drag racing, but it's being revisited and reinvented these days for use with the max-handling trend, so we figured it was a good time to have a fresh look at the process.

Some mini-tub jobs involve removing the stock inner and outer wheelhouses entirely and replacing them with fabricated semicircular tubs. The upside of doing that is it gives the most possible rubber room, but the downside is the tub-to-quarter-panel seam usually can't be welded without quarter-tweaking problems, so the tubs are usually silicone-beaded to the quarters, lending potential for leakage and flexibility problems. Most muscle car owners would prefer to give up a tiny bit of tread clearance in favor of leaving the stock outer half of the wheelwells in place, complete with the factory-welded seams at the wheelwell lips. When the outers are left in the stock position, the inners can be cut and moved inboard to gain room for 1 to 3 extra inches of tire width.

The process is shown here on a '69 Plymouth Satellite with the work done by Mitch's Custom Fabrication in Monrovia, California, but the steps will be similar for most muscle cars. Make sure to read the sidebars for more tips before you break out the Sawzall.

14/15These Detroit Speed & Engineering offset rear shackles are one tactic you can use to move leaf springs inboard; matching offset front hangers will be required.

Think Before You HackMini-tubbing has a lot of trickle-down effects you should consider before you perform the work. Here's a checklist of stuff to know before you go.

* Wheeltub enlargement might not give you more rubber clearance if suspension components are still in the way. Leaf springs may need to be relocated inboard, shock mounts may need to be altered, and on coil spring cars, custom-notched or bent control arms may be needed. Perhaps it's a good time to swap to coilovers?

* If you move your leaf springs inboard, it might create the need for a narrowed gas tank.

* Look at your car carefully to figure out how you will hinge and spring the decklid if the tub work gets in the way of the stock system.

* Consider if you want to retain a back seat or figure out how to narrow or notch your existing back seat if the new, larger tubs get in the way.

* If you are going to get a different rear axle, plan to do that as part of the mini-tub process so you can order it in a custom width to maximize tire room. We suggest getting your wheels and tires first, then propping them in the wheelwells so you can measure inside to inside to determine the required overall width of the axle assembly, keeping in mind that brakes will add to the width.

15/15This is one of Detroit Speed & Engineering's Deep Tub kits installed in a second-gen Camaro.

Custom Mini-Tub KitsWhile many of the muscle car-era cars can gain tire room by widening the stock wheeltubs, others are more complicated, and the job can be simplified and tire room maximized by using custom kits with new sheetmetal stampings. For example, if you have a '68 to '72 Nova or a '70 to '81 Camaro or Firebird, look into the Deep Tub kits from Detroit Speed & Engineering (www.detroitspeed.com).

For '79 to '04 Mustangs, the wheel arches are not a perfect semicircle, so many manufacturers offer perfect-fit tubs in the correct shape. Try DMC Racing (www.dmcracing.com), Team Z Motorsports (www.teamz motorsports.com), Auto Weld (www.autoweldchassis.com), or Wolfe Racecraft (www.wolferacecraft.com), among many others. Wolfe also makes a kit for fourth-gen Camaros and Firebirds.

If you have a C5 or C6 Corvette, you're not out of luck just because the body is plastic. Lingenfelter Performance Engineering (www.lingenfelter.com) offers composite tubs and fiberglass floor extensions to fit truly huge meats.